Pressure mechanism for wood grinders and the like



Dec. 22, 1959 c. L. HORNBERGER Filed April 3, 1957 INVENTOR CLARENCE L-HORNBERGER ATTORNEY atent @fiice Patented Dec. 22, 1959 PRESSUREmCHANlSM FOR WOOD GRINDERS AND THE LIKE Clarence L. Hornherger, ManheimTownship, Lancaster County, Pa., assiguor to Armstrong Cork Company,Lancaster, Pa., a corporation of Pennsylvania Application April 3, 1957,Serial No. 650,409

4 Claims. (Cl. 241282) This invention relates to a fluid pressureactuated power unit and is concerned more particularly with a power unitfor actuation of the pressure foot of a wood pulp grinder.

In grinding wood for use in the preparation of fibers for fiberboardmanufacture, for paper pulp preparation, and the like, it is customarywith the so-called Great Northern grinders to provide two or morewood-receiving pockets spaced circumferentially about the grindingstone. A pressure foot is provided in each of these pockets to pressbolts of wood which are charged into the pocket into engagement with thegrinding stone. Upon completion of each grinding cycle, the pressurefoot is retracted, and a new charge of wood is deposited into the pocketfor grinding.

Conventional practice has been to use water as the fluid under pressurefor actuation of the power unit for the pressure foot. Any leakage ofwater from the hydraulic system which might pass into the pocket or intothe grinder pit in these hydraulic actuated units did not contaminatethe ground wood stock. Oil has not been used extensively as theactuating fluid because of possible stock contamination. Leakage mostfrequently occurs through packing failure at the piston rod as a resultof damage to the piston rod or as a result of excessive wearing of it.This problem of minimizing sealing failure is aggravated where thepressure foot is of great weight and is massive and is supported on theoutboard end of the piston rod, without adequate guiding of the pressurefoot to minimize wear on the piston rod and to reduce the likelihood ofbending or other permanent damage to the rod.

An object of the invention is to provide a fluid under pressure operatedcylinder and piston power unit in which guiding of the member actuatedby the power unit is separated from the thrust element of the powerunit.

Another object of the invention is to provide a power actuating unit forthe foot of a wood grinder or the like in which the pressure foot isguided independently of the actuating unit.

In wood grinding, there is a real production advantage to be gained ifthe pressure foot can be retracted quickly for charging of the wood intothe pocket and can be moved quickly in a reverse direction aftercharging has been completed to bring the wood into engagement with thegrinding stone. This rapid retraction and rapid gripping of the woodcannot be accomplished with the conventionally used large diameterhydraulic power units unless extremely large valves, pipes, and portsare provided in the system, for large volumes of fluid must be inlettedinto and discharged from the power unit in a short time interval toeffect such rapid move ment of the piston in the unit. Large diameterhydraulic power units have been required in the past to provide anadequately strong piston rod and piston to support the weight of themassive pressure foot and to provide an extensive sealing surface at thepiston rod in an effort to reduce leaks in the system.

Another object of the invention is to provide a small diameter fluidpressure power unit in a system including a heavy, massive pressuremember which, because of the small size of the power unit, may beoperated at high speed without large valves, pipes, ports, and the like.

Other objects of the invention will be clear from consideration of thefollowing description of an embodiment of the invention which will bedescribed in conjunction with the attached drawing, in which:

Figure 1 is a diagrammatic sectional view of a wood grinder embodyingthe hydraulic power unit of the present invention;

Figure 2 is a sectional view taken on the line II--II of Figure 1.

The unit shown in the drawing comprises a grinding stone 2, a woodpocket 3, and a pressure foot 4 arranged to press bolts of wood receivedin the pocket 3 into engagement with the rotating grinding stone 2 toreduce the wood to fibrous form for use in the manufacture offiberboard, for instance. Movement of the pressure foot 4 in theapplication of pressure thereto to effect grinding is provided by afluid pressure cylinder and piston power unit or fluid power motor 5which is received within a housing 6 mounted upon a stand 7. A gate 8closes the top of the wood pocket 3 and is actuated by a power cylinderand piston unit 9.

The pressure foot may be of large size and great weight where thegrinding unit includes a 54" diameter stone, for example, having a 34"wide working face, used for grinding wood for fiberboard manufacture. Asmentioned previously, one of the problems involved with a pressure footof this size and weight is to guide the same properly for rapidactuation and for operation at relatively high pressure during thegrinding cycle. It is not feasible to mount the unit in such fashionthat it is supported by the piston rod of the hydraulic cylinder powerunit. In the embodiment shown in the drawing, the pressure foot 4 issupported independently of the power unit 5. This is effected by use ofa sleeve 10 which is guided in bearings 11 and 12.

Bearing 11 is received within the forward end of housing 6 in fixedposition therein. A pair of sealing rings 13 and 14 are provided forwardof the bearing 11 and engage the outer cylindrical surface of sleeve 10.A retaining ring 15 is fixed to the housing 6 and holds the seals inposition within the housing.

Bearing 12 is mounted on the sleeve 10, and the bearing 12 slides withinthe machined inner cylindrical surface of the housing 6. A flangedretaining ring 16 is secured to sleeve 10 and holds bearing 12 in fixedposition on the sleeve 10 for its sliding movement within housing 6.

The forward end of sleeve 10 is provided with a flange 17 which may beof annular configuration and may be welded to sleeve 10. The pressurefoot 4 preferably is bored to receive the flanged end of the sleeve 10and is bolted thereto by bolts 18.

From the foregoing, it will be clear that the pressure foot 4 is fullysupported by the sleeve 10 which is mounted for axial movement inhousing 6 to bring the pressure foot 4 into engagement with bolts ofwood received in the pocket 3 and to press the bolts of wood intoengagement with the grinding wheel 2 for grinding upon application offorce to the pressure foot.

This axial movement of the sleeve and the pressure foot attached to itand the application of pressure to the pressure foot for grinding isimparted by the fluid pressure actuated power unit 5 which is preferablya double acting piston and cylinder power unit deriving its power fromoil, water, or other fluid under pressure applied to the piston and thecylinder. The unit 5 is 3 mounted within the sleeve 10. The rear endbell 19 of the unit is provided with a clevis connection 20 whichcooperates with a tongue 21 welded to a reinforced end cap 22 which isbolted or otherwise secured to a flange 23 on housing 6. A clevis pin 24connects the members 20 and 21 of the clevis connection, the pin 24being received within a self-aligning bearing member 25 to provide forlimited self-adjusting movement of the power unit during movement of thesleeve 10.

The piston rod 26 of the power unit 5 is provided with a connection forefiecting sliding movement of the sleeve 10. In the embodiment shown,there is provided a threaded outboard end 27 which receives a threadedtongue connection 28. The connection 28 is associated with thebifurcated prongs of a clevis connection 29 provided on pressure foot 4.A clevis pin 30 and a selfaligning bearing 31 similar to the connectionon the end bell 19 are provided to permit the necessary minorselfadjusting movements of the power unit 5 during operation toaccommodate radial irregularities in the axial movement of the sleeve.

The usual pipe connections 32 and 33 to the upper and lower end bells ofthe double acting power unit 5 are provided for admission and exhaust ofactuating fluid for the unit.

In operation of the device, fluid under pressure may be applied throughpipe 32 to the piston of double acting fluid power motor 5. This willserve to move piston rod 26 to which pressure foot 4 and guiding sleeveare attached in a direction toward the grinding wheel 2. The cylinder offluid power motor 5 which is attached to end cap 22 on the housing 6remains stationary except for the limited adjusting movement provided bythe clevis and self-aligning bearing connection 24-25 between the endbell 19 and the end cap 22 and the similar connection 30-41 between thepiston 26 and the pressure foot 4. Sleeve 10 will be guided in itsmovement by hearing 11 affixed to housing 6 and bearing 12 affixed tosleeve 10. When it is desired to reverse the direction of movement ofpressure foot 4, fluid under pressure may be applied through pipe 33 tothe opposite side of the piston of fluid power motor 5.

With the unit shown in the drawing, a high pressure, small diameter,fluid actuated power unit is provided which may be arranged for rapidmovement of the piston in the power unit without the requirement forextremely large valves, pipes, and ports, usually required where largediameter, hydraulic cylinder units are provided for actuating thepressure foot in pulpwood grinders. Also, the arrangement provides forguiding of the pressure foot during its travel by means whollyindependent of the power unit, and thus the piston rod of the power unitdoes not support the weight of the pressure foot and the reactive thruston the piston rod during the high pressure grinding cycle is essentiallyparallel to the axis of the rod, minimizing wear on the rod andpermitting good sealing to be efiected between the piston rod and thecylinder and reducing the possibility of fluid leakage from the powerunit which might result in contamination of the wood pulp stock.

While the invention has been described in particular relationship to apulpwood grinder, the arrangement will be useful in other applications.It will be particularly useful where the member actuated by the powerunit,

such as the pressure foot in the embodiment illustrated, is relativelyheavy.

I claim:

1. A fluid pressure actuated power unit comprising a housing, a sleevereceived within said housing, bearing means supporting said sleeve forsliding movement relative to said housing, a fluid pressure actuatedpower motor including a piston and cylinder, said power motor beingdisposed within said sleeve, and means operatively connecting said powermotor to said housing outboard with respect to said sleeve and to saidsleeve for imparting axial movement to said sleeve upon relativemovement between said piston and cylinder upon application of fluidunder pressure thereto.

2. In a wood grinder the combination of a housing, a sleeve receivedwithin said housing, bearing means supporting said sleeve for slidingmovement relative to said housing, a pressure foot attached to andclosing one end of said sleeve, a double acting fluid pressure actuatedpower motor including a piston and cylinder disposed within said sleeve,and means operatively connecting said power unit to said housing and tosaid sleeve for imparting axial movement to said sleeve upon relativemovement between said piston and cylinder upon application of fluidunder pressure thereto.

3. In a wood grinder including a wood pocket and a pressure foot movablein said pocket, the combination of a power unit for actuation of saidpressure foot comprising a housing, a sleeve for carrying said pressurefoot, said sleeve being received within said housing, hearing meanssupporting said sleeve for sliding movement relative to said housing, anend cap secured to the outboard end of said housing, a double actingfluid pressure actuated power motor disposed within said sleeve, andmeans connecting said power motor to said end cap and said sleeve forsliding said sleeve relative to said housing.

4. In a wood grinder including a wood pocket and a pressure foot movablein said pocket, the combination of a power unit for actuating saidpressure foot comprising a housing; a sleeve for carrying said pressurefoot, said sleeve being received within said housing; bearing meanssupporting said sleeve for sliding movement relative to said housing; adouble acting fluid pressure actuated motor for powering the movement ofsaid sleeve, said unit including a cylinder, a piston movable in saidcylinder, and a piston rod connected to said piston; means connectingsaid cylinder to said housing for slight pivotal and rotary motionrelative thereto; and means connecting said piston rod to said sleevefor similar movement to accommodate radial irregularities in the axialmove ment of said sleeve relative to said housing.

References Cited in the tile of this patent UNITED STATES PATENTS556,196 Molas Mar. 10, 1896 1,979,373 Ellis Nov. 6, 1934 2,634,587 PtakApr. 14, 1953 2,703,206 Lyall Mar. 1, 1955 FOREIGN PATENTS 15,979 NorwayJan. 28, 1907 352,626 Germany Apr. 29, 1922

